feat(sites): cross-process site rate limit via PG token bucket

Migration 0041_rate_limit adds rate_limit_bucket. PgTokenBucket (@umt/db)
refills and takes tokens under SELECT ... FOR UPDATE on the DB clock and
polls with jitter within a wait budget; penalize() carries Retry-After.
Site adapters get createSharedSiteRateLimiter (key site:<id>), shared by
api / worker / worker:agent, with an in-process serial queue in front and
a local fallback when the bucket is unavailable.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/adapters/src/sites/index.ts

@@ -38,7 +38,14 @@ export {
   mteamSearchParams,
   parseMteamResult,
 } from "./mteam/spider.ts";
-export { createSiteRateLimiter, type RateLimiterOptions, type SiteRateLimiter } from "./rate-limit.ts";
+export {
+  createSharedSiteRateLimiter,
+  createSiteRateLimiter,
+  type RateLimiterOptions,
+  type SharedBucketPort,
+  type SharedRateLimiterOptions,
+  type SiteRateLimiter,
+} from "./rate-limit.ts";
 export {
   createSiteAdapter,
   getSiteAdapter,